This invention relates to tamper detection and in particular to detection of attempts to tamper with secure equipment, for example postage meters.
Postage meters are provided for the metering of postage charges applied to postal items. The postage meter includes electronic circuit for carrying out accounting functions to maintain an accurate record of funds available for franking postal items and to decrement those funds with postal charges applied to items. The postal authority is dependent upon the accounting circuits of the postage meter to ensure proper payment by a user of the postage meter for the value of postage charges used and applied to postal items. Accordingly it is well known to ensure that the accounting circuits are maintained in a secure manner to prevent fraudulent attempts to effect mal-functioning of the accounting circuits with the intent to obtain postage value without making a corresponding payment for that value to the postal authority. The accounting circuits are maintained secure by housing the accounting circuits in a secure housing. The housing is sealed so that it is necessary to break the seal in order to gain access to the circuits within the housing. Accordingly if the seal is broken it indicates that an unauthorised attempt has been made to gain access to the interior of the housing and the circuits contained therein. The need to remove and replace seals when authorised access is required to the interior of the housing is inconvenient and furthermore replacement of a seal by an unauthorised replacement seal may not be detected.
According to the present invention tamper detection apparatus for detection of unauthorised access to an element housed within a secure housing includes at least one sensor located within the secure housing and responsive to opening of said housing.